Currently a hydrostatic drive garden tractor employs a final drive differential and basic design that is shared with the gear drive tractors of that manufacturer. The hydrostatic models feature an independent rear PTO. The gear drive models employ a drive clutch at the engine and a range transmission ahead of the speed transmission so that the independent rear PTO may not be employed.
The new invention places the drive clutch in the transaxle at the primary reduction section and replaces the separate range transmission with two additional, more desirable creep speeds in the main transmission so that the gear drive models may employ the very same rear PTO system currently available only with hydrostatic drive and so that hydro and gear models may share additional components and assembly to further reduce cost.
Currently many hydrostatic drive tractors feature a single range of speeds. When these tractors include a second speed range, typically design limitations dictate that this second speed be a faster transport speed somewhat closely related to the slower speed so that there is no real improvement in creep speed performance as when snow blowing or rototilling.
The present invention greatly enhances the efficient operation of a hydrostatic drive tractor by providing both a faster and a slower range of speeds. The two additional speeds only require that two additional gearsets be added to a present single range tractor. The slow speed enjoys the multiplied reduction of three gearsets for positive control creep speed. A safety neutral is also provided.
Currently some gear drive tractors employ an auxiliary range transmission to provide a number of creep slow work speeds. The disadvantages of which are:
1. A lack of inherent safety; garden tractors are largely operated by nonprofessionals with little understanding of torque multiplication principles and means. The concept of first, second, third has automotive precedent; but the concept of third low and third high has little meaning.
2. Cumbersome creep engagement requires the movement of two gearshift levers.
3. Additional unnecessary speeds, i.e. creep reverse and nearly redundant top speed low.
4. Poor forward/reverse shuttle operation from creep forward to normal reverse.
5. Often the range transmission will also reduce a rear PTO speed.
6. Excessive costs.
Currently other gear drive garden tractors include a creep speed gear train within the primary transmission. The disadvantages of which as heretofore utilized include:
1. The need to pass the gearshift lever through a normal speed to engage creep and the associated cumbersome reverse shuttle function.
2. Utilization of a sliding gear to engage creep with inherent weakness and gear clashing.
3. An additionally required reduction support shaft.
4. Excessive costs.
These disadvantages are overcome by the new invention wherein a primary transmission creep speed utilizes the gearsets of two normal speeds to contribute to the creep speed reduction. There are no dangerously small pinions and all gearsets are in constant mesh so that sintered metal may be used to reduce cost. There are no speed increasing drives requiring costly additional reduction elsewhere in a transaxle. The shift means are comprised primarily of the gearsets themselves and no separate lay shafts are required. All speeds are engaged with a familiar H pattern movement of the single gearshift lever with reverse located opposite a convenient forward speed.
Concerning a PTO system, currently few garden tractors feature a category O rear PTO as suggested by the ASAE, American Society of Agricultural Engineers, so that owners of these tractors may not utilize standardized implements available. Also, there has been no real progress in the standardization of front and middle mounted work tools so that driven attachments designed for a certain model tractor may not be used with any other make or model.
The new invention shows a front middle and rear PTO system that makes all three outputs available at reasonable cost and suggests a format for standardization of front and middle implements.
Furthermore, a controversy exists over the proclaimed "too fast" 2000 rpm ASAE proposed garden tractor rear PTO speed and the also proclaimed "too slow" 540 rpm ASAE compact tractor standard. The present invention shows a tractor featuring both PTO speeds at little cost to utilize implements designed for garden and compact tractors alike.
Concerning ATV cycles and their use as small tractors, the new invention is shown to enhance their performance and extend their application in tractor mode.
Currently some of these cycles are being fit with work tools such as lawn mowers. Typically the cycle is operated in a lowest transmission speed at a low engine speed to hold a reasonable and effective work speed.
The new invention is shown in a variation to provide two extreme reduction work speeds and a safe reverse speed within the primary transmission. A second variation shows a separate range transmission employing the new invention to provide extreme reduction work speeds.
The slow work speeds will prevent accidental fast run away of a cycle with a separately powered mower in operation.